Add typewriter effect

src/config.rs

@@ -0,0 +1,130 @@
+//! Game configuration, loaded from `./game.ini`.
+//!
+//! Two settings today:
+//! - `typewriter_effect` (bool, default `true`) — animate level prompts
+//!   character-by-character as they appear in the log.
+//! - `typewriter_speed_cpm` (u32, default `1000`) — typing speed in
+//!   characters per minute (~60 ms per character).
+//!
+//! Missing keys fall back to defaults. Missing file falls back to all
+//! defaults. Comments (`#` or `;`) and `[sections]` are ignored.
+
+use std::path::PathBuf;
+use std::time::Duration;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct GameConfig {
+    pub typewriter_enabled: bool,
+    pub typewriter_speed_cpm: u32,
+}
+
+impl Default for GameConfig {
+    fn default() -> Self {
+        Self {
+            typewriter_enabled: true,
+            typewriter_speed_cpm: 1000,
+        }
+    }
+}
+
+impl GameConfig {
+    /// How long each character takes to appear during the typewriter
+    /// animation. Falls back to the default speed if `speed_cpm` is 0.
+    pub fn char_duration(&self) -> Duration {
+        let cpm = if self.typewriter_speed_cpm == 0 {
+            Self::default().typewriter_speed_cpm
+        } else {
+            self.typewriter_speed_cpm
+        };
+        Duration::from_millis(60_000 / cpm as u64)
+    }
+}
+
+pub fn config_path() -> PathBuf {
+    PathBuf::from("game.ini")
+}
+
+pub fn load() -> GameConfig {
+    match std::fs::read_to_string(config_path()) {
+        Ok(content) => parse(&content),
+        Err(_) => GameConfig::default(),
+    }
+}
+
+pub fn parse(content: &str) -> GameConfig {
+    let mut cfg = GameConfig::default();
+    for line in content.lines() {
+        let line = line.trim();
+        if line.is_empty()
+            || line.starts_with('#')
+            || line.starts_with(';')
+            || line.starts_with('[')
+        {
+            continue;
+        }
+        let Some((key, value)) = line.split_once('=') else {
+            continue;
+        };
+        let key = key.trim().to_lowercase().replace(' ', "_");
+        let value = value.trim();
+        match key.as_str() {
+            "typewriter_effect" | "typewriter_enabled" => {
+                if let Ok(b) = value.parse::<bool>() {
+                    cfg.typewriter_enabled = b;
+                }
+            }
+            "typewriter_speed" | "typewriter_speed_cpm" => {
+                if let Ok(n) = value.parse::<u32>() {
+                    cfg.typewriter_speed_cpm = n;
+                }
+            }
+            _ => {}
+        }
+    }
+    cfg
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn defaults() {
+        let cfg = GameConfig::default();
+        assert!(cfg.typewriter_enabled);
+        assert_eq!(cfg.typewriter_speed_cpm, 1000);
+        // 1000 cpm = 60 ms per char
+        assert_eq!(cfg.char_duration().as_millis(), 60);
+    }
+
+    #[test]
+    fn parser_reads_both_underscored_and_spaced_keys() {
+        let ini = "\
+            # comment\n\
+            ; another comment\n\
+            [section]\n\
+            typewriter effect = false\n\
+            typewriter_speed_cpm = 240\n\
+        ";
+        let cfg = parse(ini);
+        assert!(!cfg.typewriter_enabled);
+        assert_eq!(cfg.typewriter_speed_cpm, 240);
+        // 240 cpm = 250 ms per char
+        assert_eq!(cfg.char_duration().as_millis(), 250);
+    }
+
+    #[test]
+    fn parser_keeps_defaults_on_garbage() {
+        let cfg = parse("typewriter_effect = maybe\ntypewriter_speed_cpm = fast\n");
+        assert_eq!(cfg, GameConfig::default());
+    }
+
+    #[test]
+    fn zero_speed_falls_back_to_default_duration() {
+        let cfg = GameConfig {
+            typewriter_enabled: true,
+            typewriter_speed_cpm: 0,
+        };
+        assert_eq!(cfg.char_duration().as_millis(), 60);
+    }
+}